Local residents are being warned to be on the guard against doorstep sellers. Hertfordshire County Council says the summer signals a sharp increase in the number of people being duped by bogus or poor quality tradesmen calling door to door.

Trading standards officers say many people end up being intimidated into buying goods or services they don't need or can't afford. The doorstep sellers strike at this time of the year because it is when most people want work done on their homes and gardens.

According to trading standards, people have been victimised after changing their minds about having their drives redone. One trader threatened to pour paint over the existing drive and another said he would carry out the work anyway.

Several residents found that, having paid for the work, it wasn't completed or was finished to a poor standard. It was impossible to get the firm to return to repair the work.

Trading standards say residents should never let themselves be pressured into making on-the-spot decisions. They say reputable companies will be happy to give you time to make up your mind or get further information.

They also say that, in many cases, duped residents have no information or false details about the company they dealt with and therefore no way of contacting the firm once they have left. This means that although they have legal rights, nothing can be done because the trader can't be traced.

Trading Standards Authorities have set up a special doorstep hotline. They ask anyone concerned about doorstep callers in their area to pass the information on by calling 0845 60 444 66 at any time.